A new copper hydroxydiphosphate Cu-3(P2O6OH)(2) was synthesized, by soft chemistry. The crystal structure was solved ab initio from X-ray powder diffraction data in the triclinic space group P1. The structure is built up from [Cu3O10](infinity) zigzag chains linked by P2O6(OH) groups to form a tridimensional framework. The [Cu3O10](infinity) chains consist of edge-sharing polyhedra. The structure contains two sorts of copper polyhedra: one CuO6 octahedron and two CuO5 pyramids. Magnetization measurements confirm the presence of divalent copper and suggest antiferromagnetic interactions at low temperature.